Hikers and winter sports aficionados who venture deep into snow country and get caught in an avalanche may find emergency beacons are less effective if the searcher is also using a diabetes monitor or insulin pump, according to a small study.
"The potential for interference between a diabetes device and an avalanche beacon (in search mode) is increased if both devices are held in close proximity and reduced if they are separated," said lead author Dr. Steven Miller, a researcher at North Shore Hospital in Auckland, New Zealand.
So-called avalanche beacons both transmit and receive signals that can be used to locate and rescue a person buried under the snow by an avalanche.
In a typical scenario, companions who escape being buried can use their transceivers to start searching immediately for the beacon signal of someone who is missing.
Previous research has shown that the transceiver searching for a signal from another beacon can be rendered less effective by interference from cell phones, MP3 players and other electronic devices, Miller and colleagues note in Wilderness and Environmental Medicine.
The devices are not themselves affected by the avalanche beacons, though.
People with type 1 diabetes need continual monitoring and adjustments to maintain an ideal balance of insulin and glucose in their blood. Implanted insulin pumps and glucose monitors can wirelessly transmit information to each other to keep blood glucose under control for weeks at a time.
For the current study, researchers examined how well two commonly used avalanche beacon-transceivers could detect signals in an open field.
Then they explored whether placing personal electronic devices such as mobile phones and two-way radios, as well as insulin pumps and blood sugar monitors for diabetes, nearby would limit the distance at which the receiver could detect another beacon’s signal.
They found that the greatest distance at which the transceiver could accurately detect the location of a transmitting beacon was about 100 feet, but the search range was reduced to just 16 feet when the beacon was placed within about 12 inches of an iPhone 4, an iPhone 5 or an insulin pump, the Animas Vibe.
One type of blood sugar monitor, the Dexcom G4 rtCGMS, didn't appear to interfere at all with the transceiver’s ability to detect a signal. And none of the devices interfered with the transmitting beacon’s ability to send its signal.
The reduction in the searching beacon’s range of detection from 100 feet to 16 feet is significant, and has the potential to delay the rescue of a buried avalanche victim, the researchers write.
"I suggest therefore that any electronic device – including an insulin pump or a continuous glucose monitor, but also a MP3, cell phone, radio, etc – is kept as far away as possible from the avalanche beacon," Miller said in an email.
To minimize the risk of signal interference, people might wear the avalanche beacon on an upper arm and then place a diabetes device lower on the body, said Dr. Lutz Heinemann, a partner and scientific consultant at Profil Institute for Clinical Research in Neuss, Germany.
"To my knowledge, many patients with diabetes (mainly type 1) do such hiking trips and I have not heard about any issues," Heinemann, who wasn't involved in the study, said by email. "I don't have data on hand about how many patients carry an avalanche beacon while hiking, but this sounds like not too common a combination."
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